反射式液晶空间光调制器电控光束偏转

为获得较大的光束电控偏转范围,使用空间分辨力高达8 m的反射式液晶空间光调制器实现了对入射632 nm激光的电控偏转。利用双光束共焦干涉方法测量了液晶空间光调制器的电控相位延迟特性,最大相移量可达3。根据二元光学理论和器件的电控相位延迟特性,设计了周期台阶相位模式和相应的加载灰度图,以最大衍射效率实现对入射光束的闪耀电控偏转。结果表明:相位模式台阶数为8时,可以实现10 mrad的光束偏转,闪耀级次衍射效率可达46%。利用二元光学的衍射模型对影响衍射效率的关键因素进行了分析,认为器件较低的填充因子和周期台阶模式相位重置点诱导的指向矢回程区是限制光束衍射效率的主要因素。     

保偏反射膜温度特性对BGOCT灵敏度影响的理论研究

采用琼斯矩阵方法对保偏膜反射相移温度特性对块状光学电流互感器（BGOCT）灵敏度的影响作了理论研究,结果表明,当温度从5.3℃变化到39℃时,表征系统灵敏度的归一化尺度因子会在一定范围内变化.表明镀制于光学玻璃电流传感头上的保偏膜反射相移温度特性影响光学电流传感器的稳定性.因此,在实际系统设计中对光学玻璃电流传感头应采取必要的温度控制或补偿措施.     

基于光学涡旋相移技术的离面位移测量

设计了基于光学涡旋相移技术的离面位移测量实验方案,实现了电子散斑干涉中相移的数字控制.该方法利用输入液晶空间光调制器中的叉形光栅产生涡旋光束,通过涡旋光束绕轴的旋转产生相移;同时,产生的涡旋光束又作为参考光与物光干涉.实验中,在物体发生离面位移前后依次输入四幅叉形光栅,产生相移步长为π/2的涡旋光束,利用CCD获得涡旋光与物光的干涉光场,从而获得离面位移场的包裹相位;再通过解包裹,获得物体离面变形的相位变化.光学涡旋相移法可应用于离面位移测量.     

270°反射式相位延迟器的设计及温度特性研究

根据薄膜的偏振效应,运用TFCALC膜系设计软件,通过在菲涅耳菱体的2个全反射面蒸镀光学介质膜的方法设计了270°反射式相位延迟器.运用归一化测量方法得到出射光相位延迟量与温度的关系,发现出射光相位延迟量随温度的变化而发生扰动,扰动的出现影响了透射偏振光的质量.研究结果表明,透射光的相位延迟量与膜料的折射率、基底与膜料之间的应力以及膜料之间的应力等因素有关.     

平板式螺旋相位板的设计与应用

传统的螺旋相位板是一种利用沿方位角方向介质材料高度递增实现对光束相位调控产生涡旋光束的光学器件,由于这种特殊的几何结构特征使其不能通过相位板的叠加而调控出射光束所携带的角量子数.本文基于坐标变换方法将介质材料沿方位角方向折射率不变而高度递增的传统螺旋相位板变换为一种介质材料沿方位角方向高度不变而折射率递增的平板式螺旋相位板.通过理论分析与数值模拟,发现本文所设计的平板式螺旋相位板不仅与传统螺旋相位板一样能够产生高质量的涡旋光束,而且平板式螺旋相位板的高度和涡旋光束携带的角量子数可以根据介质材料的折射率选取而任意调节.为了实际应用的需要,可以通过叠加多层平板式螺旋相位板以获得不同角量子数的涡旋光束.这种平板式螺旋相位板在光传输、光通信等领域具有广阔的潜在应用价值.     

偏振相移与相位共轭结合的散射光聚焦技术研究

散射介质对光的随机散射作用是制约其光学聚焦和成像的重要因素，光学相位共轭技术能够通过对散射光场共轭还原实现透过散射介质的光学聚焦和成像，其中散射光场相位的获取是共轭还原的核心。阐述了偏振相移的基本原理，将偏振相移与相位共轭技术相结合，设计了新的基于偏振相移的数字光学相位共轭系统。采用633 nm的HeNe激光器作为系统光源，毛玻璃作为散射介质开展散射光聚焦实验研究。实验结果表明:该装置能够成功实现透过散射介质的光学聚焦，其中聚焦点与背景光强的比值可达约400倍。     

反射相移色散对OCS灵敏度影响的理论研究

以琼斯矩阵为数学工具,利用理论分析和计算机仿真的方法研究了单层保偏反射膜反射相移的色散特性及其对光学电流传感器灵敏度的影响.在光学电流传感器系统中,光源的驱动电流与环境温度改变,都会造成光源峰值波长移动.由于反射膜上产生的反射相移的色散特性,会使光学电流传感器的灵敏度随光源波长的变化而改变.研究结果表明,反射相移的色散特性会对输出曲线的尺度因子产生明显的影响.因此,光源的恒温控制与光源驱动电流的恒流控制是必要的. 本研究结果可为光学电流传感器的研究设计人员提供有用的参考.     

用于Faraday电流传感器的保偏膜光学电流传感元件

本文报告了一种用于高电压电流传感系统的、带有保偏反射介质膜的光学法拉第电流传感头的设计与性能测试结果.实验结果表明:该传感头的灵敏度与无保偏反射介质膜但其它参数均相同的传感头相比提高了86.7%.文中还介绍了该传感头的五项优点.     

薄介质板结构中有限光束的多次反射及其重构

利用有限光束在薄介质板结构中多次反射及其重构揭示有限波束透射光束反常侧向位移产生的物理机制;证明了物理上有限光束出现反常侧向位移的限制条件与稳态相位法成立的数学条件是一致的.通过数值模拟表明,透射光束的反常侧向位移是因为有限光束在薄介质板结构中每个经过多次反射后具有不同相移的平面波分量重构的结果.对于整个波束而言,透射光束的反常侧向位移是薄介质板结构中多次透射或反射的波束相干叠加产生的.     

新型液晶光学相控阵的特性研究

将液晶作为平板光波导的上包层,构建了液晶光学相控阵器件.根据Frank-Oseen液晶连续体弹性形变理论与光栅衍射理论,研究分析了基于这种新型结构下液晶光学相控阵的传输特性,输出衍射特性和其它性能特性.研究结果表明,器件的传输电控相位延迟可以实现更大的光程差;阵列电极周期数目、电极宽度、电极间隔宽度等结构参量对器件的输出衍射光束的光强分布和半峰值全宽度影响很大,同时光束扫描的可行性得到论证;器件的响应时间提高了一个数量级,且其色散性能获得改善.为以后研制新型液晶光学相控阵提供了理论基础与技术设计依据.     

An analysis of optimal structural features in the peacock tail feather

This paper presents an analysis of the optimal structural features in the peacock tail feather. Peacock tail feathers are highly optimized in three respects. The feathers are highly efficient structures that can support their own weight in a deployed position. The feathers are also optimized for producing thin-film colours with a high degree of lustre. The feathers also have a structure which produces intricate patterns with a high degree of aesthetic merit. There are structural features that allow simultaneous optimization in the different areas of performance. In particular, the thin-film sandwich structure is ideal for producing optimal structural performance and optimal optical performance.     

New techniques for laser microprocessing of photovoltaic devices based on thin-film a-Si:H

Laser-controlled ablation of individual layers in glass/TCO/thin-film silicon/metal structures is essential for cell isolation and monolithic interconnection in thin-film silicon photovoltaic technologies. More recently, the potential application of laser scribing techniques for the development of photovoltaic matrix position sensors based on a-Si:H has generated much activity, requiring an excellent control in laser-generated patterns obtained by direct material ablation.This work is aimed to determine process parametric windows for a-Si:H thin-film ablation processes using UV ns laser sources in thin-film a-Si:H-based devices. The study is focussed on direct writing techniques using UV sources. We present ablation threshold measurements and process quality assessment using advanced optical microscopy techniques. Moreover only fully commercial laser sources in the ns regime has been used, bearing in mind that thin film based photovoltaic technologies are still demanding further reduction in production costs and, nowadays, ultrafast sources are beyond their scope both for the investment and running cost of those equipments.     

两种后处理方法对HfO2薄膜性能的影响

利用电子束蒸发和光电极值监控技术制备了氧化铪薄膜,并分别用两种后处理方法(空气中退火和氧等离子体轰击)对样品进行了处理.然后,对样品的透过率、吸收和抗激光损伤阈值进行了测试分析.实验结果表明,两种后处理方法都能不同程度地降低了氧化铪薄膜的吸收损耗、提高了抗激光损伤阈值.实验结果还表明,氧等离子体轰击的后处理效果明显优于热退火,样品的吸收平均值在氧等离子体后处理前后分别为34.8 ppm和9.0 ppm,而基频(1 064 nm)激光损伤阈值分别为10.0 J/cm2和21.4 J/cm2.     

Influence of thermal treatment on the performance of copper phthalocyanine thin-film transistors

Organic thin-film transistors (OTFTs) with bottom-gate and bottom-contact configuration based on copper phthalocyanines (CuPc) as active layer were fabricated. The performance of CuPc OTFTs was studied before and after thermal treatment on CuPc layer. The values of the threshold voltage before and after thermal treatment are −6.3 and −5.7 V, respectively. The field-effect mobility values in saturation regime of CuPc thin-film transistors before and after thermal treatment are 0.014 cm²/Vs and 0.0068 cm²/Vs, respectively. The experimental results indicate that there is a heavy decay on the mobility of CuPc based OTFTs mostly due to the crystalline morphology change induced by the thermal treatment, and absolute value of the threshold voltage after thermal treatment decreases with the decrease of the CuPc film thickness and the roughness.     

New method to measure whole-wavelength transmittance of TCO substrates for thin-film silicon solar cells

High transmittance of transparent conductive oxide (TCO) substrates is one of the most important factors for achieving high efficiency in thin-film silicon solar cells. Immersion (IM) method with CH₂I₂ liquid is widely used for the evaluation of optical properties (transmittance, reflectance and absorption) for TCO substrates with textured surface in order to reduce the scattering at the TCO surface. However, in order to measure transmittance accurately, three problems have been found. (1) CH₂I₂ liquid itself absorbs the light in short wavelength region. (2) The transmittance around the absorption edge of CH₂I₂ liquids is very sensitive to its amount. (3) Scattering cannot be suppressed when the scattering surfaces are more than 2 surfaces (for example, TCO on reactive ion etching (RIE) processed glass). To overcome these problems, we proposed a new setup to measure optical properties of TCO substrates by holding the samples inside the integral sphere. As the results, we have confirmed that their absorption in all wavelength could be measured accurately and the transmittance measured by the new method was well consistent with the external quantum efficiency (EQE) of the fabricated cell while the transmittance measured with conventional IM method showed differently. Therefore, this new method could be a useful tool to evaluate TCO substrates for thin-film silicon solar cells.     

高温超导平面电路光刻工艺

在研究了传统光刻工艺的基础上 ,针对高温超导平面电路自身对工艺的要求 ,结合高温超导薄膜的特点 ,提出了几点工艺方法上的改进 ,解决了传统光刻工艺中存在的几个问题。实验结果表明 ,这种新的工艺方法不仅增加了高温超导平面电路制备工艺的稳定性 ,而且提高了样品的可重复性。     

使线偏振光变为圆偏振光——薄膜1/4波片的设计

在一个折射率为N_2的基片上,镀制一层折射率为N_1=(N_0·N_2)~(12),厚度为d_1=λ/4(N_1~2-N_0~2Sin~2φ_0)~(-1/2)的透明介质薄膜,当一束波长为λ的线偏振光以特定的方位角α,在合适的入射角φ_0下,倾斜辐射到薄膜表面上时,可得到的反射光线为圆偏振光。     

High-performance Zinc-Tin-Oxide thin film transistors based on environment friendly solution process

Zinc-Tin-Oxide (ZTO) thin films were fabricated using a simple and eco-friendly sol-gel method and their application in thin film transistors (TFTs) was investigated. Annealing temperature has a crucial influence on the structure and electrical properties of sol-gel ZTO thin films. The ZTO thin films annealed at 300–600?°C revealed smooth and uniform surfaces with amorphous state, in addition, a high optical transparency over 90% of the ZTO films in the visible range was obtained. The electrical performance of ZTO TFTs showed obvious dependence on annealing temperature. The ZTO TFTs annealed at 500?°C showed a high carrier mobility of 5.9?cm²/V, high on/off current ratio (I_on/off) of 10⁶-10⁷, and threshold voltage (V_th) of 1.03?V. To demonstrate the application of sol-gel ZTO films in low-power display fields, we also fabricated ZTO TFTs with a solution-processed high-permittivity (high-k) ZrTiO_x dielectric layer. The ZTO/ZrTiO_x TFTs showed high mobility of 17.9?cm²/V and I_on/off of 10⁵-10⁶?at a low operation voltage of 3?V, indicating that Indium-free ZTO thin films would be potential candidates for low cost, high performance oxide TFT devices.     

Zinc oxide nanoparticles for improvement of thin film photovoltaic structures’ efficiency through down shifting conversion

The paper presents the idea to improve the performance of thin film photovoltaic cells by a light capture enhancement through the introduction of down shifting energy converters. Luminescent down shifting layers convert high-energy photons (UV light) into low-energy ones (visible light), which are more efficient in a photovoltaic conversion. For this purpose, the application of a thin layer composed of zinc oxide (ZnO) nanoparticles deposited onto a thin film solar cell is proposed. The paper presents both experimental and theoretical results of this approach. Conducted investigations include an analysis of ZnO nanoparticle layers, deposited in two independent technology methods. The results showed that ZnO nanoparticles have a great potential of application as down converting layers and can be implemented to improve the efficiency of photovoltaic cells, especially in the field of thin film PV structures. The proposed new deposition method can potentially be used in some industrial photovoltaic applications.     

Extraction of density-of-states in amorphous InGaZnO thin-film transistors from temperature stress studies

The instability of amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) with different active layer thicknesses under temperature stress has been investigated through using the density-of-states (DOS). Interestingly, the a-IGZO TFT with 22 nm active layer thickness showed a better stability than the others, which was observed from the decrease of interfacial and semiconductor bulk trap densities. The DOS was calculated based on the experimentally-obtained activation energy (E_A), which can explain the experimental observations. We developed the high-performance Al₂O₃ TFT with 22 nm IGZO channel layer (a high mobility of 7.4 cm²/V, a small threshold voltage of 2.8 V, a high I_on/I_off 1.8 × 10⁷, and a small SS of 0.16 V/dec), which can be used as driving devices in the next-generation flat panel displays.